Metabolic glycan probes have emerged as an excellent tool to investigate vital questions in biology. Recently, methodology to incorporate metabolic bacterial glycan probes into the cell wall of a variety of bacterial species has been developed. In order to improve this method, a scalable synthesis of the peptidoglycan precursors is developed here, allowing for access to essential peptidoglycan immunological fragments and cell wall building blocks. The question was asked if masking polar groups of the glycan probe would increase overall incorporation, a common strategy exploited in mammalian glycobiology. Here, we show, through cellular assays, that E. coli do not utilize peracetylated peptidoglycan substrates but do employ methyl esters. The 10-fold improvement of probe utilization indicates that (i) masking the carboxylic acid is favorable for transport and (ii) bacterial esterases are capable of removing the methyl ester for use in peptidoglycan biosynthesis. This investigation advances bacterial cell wall biology, offering a prescription on how to best deliver and utilize bacterial metabolic glycan probes.

中文翻译：

---

受保护的 N-乙酰基胞壁酸探针通过代谢标记改善细菌肽聚糖的掺入

代谢聚糖探针已成为研究生物学中重要问题的绝佳工具。最近，已开发出将代谢细菌聚糖探针结合到多种细菌物种的细胞壁中的方法。为了改进这种方法，这里开发了肽聚糖前体的可扩展合成，允许访问基本的肽聚糖免疫片段和细胞壁构件。有人问，掩蔽聚糖探针的极性基团是否会增加整体掺入，这是哺乳动物糖生物学中采用的一种常见策略。在这里，我们通过细胞分析表明，大肠杆菌不使用过乙酰化肽聚糖底物，但使用甲酯。探针利用率提高 10 倍表明 (i) 掩蔽羧酸有利于转运，(ii) 细菌酯酶能够去除甲酯用于肽聚糖生物合成。这项研究推进了细菌细胞壁生物学，为如何最好地传递和利用细菌代谢聚糖探针提供了处方。